Protonolysis reactions of [(Me3Si)2N] 3Ln(μ-Cl)Li(thf)3 with tBuSH or EtSH: Isolation, structures and catalytic properties of dinuclear complexes [{(Me 3Si)2N}2Ln(μ-StBu)]2 and tetranuclear complexes [Li(thf)4]-[{(Me3Si)...

Article abstract of DOI:10.1002/ejic.200601132

Reactions of [(Me₃Si)₂N]₃Ln(μ-Cl) Li(thf)₃ (1: Ln = Pr; 2: Ln = Sm) with an equimolar amount of tBuSH or EtSH gave rise to four amidolanthanide alkylthiolate complexes [{(Me ₃Si)₂-N}₂Ln(μ-StBu)]₂ (3: Ln = Pr; 4: Ln = Sm) and [Li(thf)₄][{(Me₃Si) ₂-N}₄Ln₄(μ₄-SEt)(μ-SEt) ₈] (5: Ln = Pr; 6: Ln = Sm). Compounds 3-6 were characterized by elemental analysis, IR and ¹H NMR spectroscopy and single-crystal X-ray diffraction, and their catalytic properties were also investigated. Compounds 3 and 4 are thiolate-bridged dimers in which each Ln atom adopts a distorted tetrahedral coordination. Compounds 5 and 6 contain a Ln₄ square plane, which is capped by a μ₄-SEt^- ligand. The edges of the square are bridged by four pairs of SEt^- ligands on both sides of the Ln₄ plane. Each Ln atom has a distorted octahedral geometry. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200601132

FULL PAPER
DOI: 10.1002/ejic.200601132
Protonolysis Reactions of [(Me3Si)2N]3Ln(µ-Cl)Li(thf)3 with tBuSH or EtSH:
Isolation, Structures and Catalytic Properties of Dinuclear Complexes
[{(Me3Si)2N}2Ln(µ-StBu)]2 and Tetranuclear Complexes [Li(thf)4]-
[{(Me3Si)2N}4Ln4(µ4-SEt)(µ-SEt)8] (Ln = Pr, Sm)
Mei-Ling Cheng,[a] Hong-Xi Li,[a] Wen-Hua Zhang,[a] Zhi-Gang Ren,[a] Yong Zhang,[a] and
Jian-Ping Lang*[a,b]
Keywords: Amidolanthanides / Alkylthiolates / Synthesis / Crystal structure / Ring-opening polymerization
Reactions of [(Me3Si)2N]3Ln(µ-Cl)Li(thf)3 (1: Ln = Pr; 2: Ln =
Sm) with an equimolar amount of tBuSH or EtSH gave rise
to four amidolanthanide alkylthiolate complexes [{(Me3Si)2-
N}2Ln(µ-StBu)]2 (3: Ln = Pr; 4: Ln = Sm) and [Li(thf)4][{(Me3Si)2-
N}4Ln4(µ4-SEt)(µ-SEt)8] (5: Ln = Pr; 6: Ln = Sm). Compounds
3–6 were characterized by elemental analysis, IR and 1H
NMR spectroscopy and single-crystal X-ray diffraction, and
their catalytic properties were also investigated. Compounds
3 and 4 are thiolate-bridged dimers in which each Ln atom
adopts a distorted tetrahedral coordination. Compounds 5
and 6 contain a Ln4 square plane, which is capped by a µ4-
SEt– ligand. The edges of the square are bridged by four
pairs of SEt– ligands on both sides of the Ln4 plane. Each Ln
atom has a distorted octahedral geometry.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
(SiMe3)2}(µ-StBu)]2 (Ln = Gd, Eu), which were prepared
from protonolysis reactions of [(Me3Si)2N]3Ln with an
equimolar amount of tBuSH in toluene/thf at –23 °C. How-
ever, these compounds readily decomposed into insoluble
polymeric materials at ambient temperature.[4]
Introduction
In the past decades, synthesis of lanthanide chalcogenol-
ates has attracted much attention due to their interesting
structures[1] and their potential applications in advanced
materials and catalytic processes.[2] Among these complexes,
only a dozen of lanthanide alkylthiolate complexes[3] have
been structurally characterized, though some lanthanide
We are interested in the preparation of amidolanthanide
benzenethiolate complexes from protonolysis reactions of
bis(trimethylsilyl)amidolanthanide(III) chloride complexes,
[(Me3Si)2N]3Ln(µ-Cl)Li(thf)3, with benzenethiol.[6] For ex-
ample, reactions of [(Me3Si)2N]3Nd(µ-Cl)Li(thf)3 with an
equimolar amount of benzenethiol gave rise to cationic tet-
ranuclear complex Li[{(Me3Si)2N}4(µ4-Cl)Nd4(µ-SPh)8].
The facile formation of this complex and other previously
reported related complexes could be attributed to the incor-
poration of lithium and chloride ions into their frame-
works.[6a] In addition, these complexes exhibited good cata-
lytic activity in the ring-opening polymerization (ROP) of
ε-caprolactone. Therefore, if the benzenethiol that was used
in the above reactions were to be replaced with different
alkylthiols, would reactions between [(Me3Si)2N]3Ln(µ-Cl)-
Li(thf)3 and the alkylthiols afford amidolanthanide thiolate
complexes with different structural frameworks? Moreover,
would the resulting complexes show better catalytic activity
in the ROP of ε-caprolactone? With these questions in
mind, we carried out reactions of [(Me3Si)2N]3Ln(µ-Cl)-
Li(thf)3 (1: Ln = Pr; 2: Ln = Sm)[7] with two common alk-
ylthiols, tBuSH and EtSH, and two neutral binuclear com-
plexes [{(Me3Si)2N}2Ln(µ-StBu)]2 (3: Ln = Pr; 4: Ln = Sm)
and two cationic tetranuclear complexes [Li(thf)4]-
[{(Me3Si)2N}4Ln4(µ4-SEt)(µ-SEt)8] (5: Ln = Pr; 6: Ln =
[4]
alkylthiolate complexes (e.g. [Gd{N(SiMe3)2}(µ-StBu)]2
and [Cp2Lu(µ-StBu)2Li(thf)2][5]) were reported in 1985.
These alkylthiolate complexes can be mainly classified into
two types: mononuclear structures {e.g. [Li(tmeda)]3[Yb-
(StBu)6]; tmeda = Me2NCH2CH2NMe2},[3c] and dinuclear
structures {e.g. [Yb(StBu)2(µ-StBu)(bipy)]2}.[3a] Most of
these compounds were prepared by metathesis of lantha-
nide halides or (substituted) cyclopentadienyl lanthanide
complexes with alkali metal thiolates,[3b,3c,3g,4] by insertion
reactions of S8 into the Ln–carbon bond[3h] or by pro-
tonolysis reactions of (substituted) cyclopentadienyl lantha-
nide complexes with alkylthiols.[3a,3d–3f,5] It is noted that re-
actions of amidolanthanide complexes with alkylthiols ap-
pear to be less explored. Aspinall et al. reported the first
amidolanthanide tert-butylthiolate complexes [Ln{N-
[a] School of Chemistry and Chemical Engineering, Suzhou Uni-
versity,
Suzhou, 215123 Jiangsu, People’s Republic of China
Fax: +86-512-65880089
E-mail: jplang@suda.edu.cn
[b] State Key Laboratory of Organometallic Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences,
200032 Shanghai, People’s Republic of China
Eur. J. Inorg. Chem. 2007, 1889–1896
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1889

M.-L. Cheng, H.-X. Li, W.-H. Zhang, Z.-G. Ren, Y. Zhang, J.-P. Lang
FULL PAPER
Sm) were isolated therefrom. Compounds 3–6 did exhibit R groups (e.g. tBu), the formation of a structure similar to
better catalytic activity in the ROP of ε-caprolactone than that of the tetranuclear lanthanide thiolate complexes (e.g.
their benzenethiolate analogues. Herein, we report the syn- 5 and 6), described later in this paper, may cause the tBu
thesis, crystal structures and catalytic properties of 3–6.
groups around the Ln4 ring to become more crowded.
Therefore, reactions of 1 or 2 with tBuSH seem to prefer the
formation of smaller complexes 3 and 4. Another reason for
the formation of complexes with larger Ln nuclearity may
be ascribed to the incorporation of Li+ and/or Cl– ions into
their structures.[6a] In the cases of 5 and 6, the larger
[Li(thf)4]+ cation that is incorporated into their structures
may to some extent stabilize the larger [{(Me3Si)2N}4-
Ln4(µ4-SEt)(µ-SEt)8]– anion by ionic interactions.
Results and Discussion
Treatment of a thf solution of 1 with an equimolar
amount of tBuSH in thf at ambient temperature led to a
yellow solution. After removal of all the volatile species in
vacuo, the residue was extracted with toluene and n-hexane,
and the insoluble LiCl precipitate was filtered off. The fil-
trate was allowed to stand at 2 °C for three days, which
resulted in the formation of yellow crystals of 3·2(thf)0.5
in 43% yield. Analogous reactions of 2 with an equimolar
amount of tBuSH in thf gave rise to 4 in 40% yield
(Scheme 1). Reactions of a thf solution of 1 or 2 in thf with
an equimolar amount of EtSH at room temperature fol-
lowed by a standard workup afforded 5·0.5C7H8 in 21%
yield or 6·C6H6 in 17% yield, respectively (Scheme 1). The
preparation of 5 and 6 was reproducible, though their yields
were relatively low, which may be due to the formation of
a large amount of insoluble material during the prepara-
tion. The yield of the two corresponding reactions de-
creased when 1 or 2 was treated with 2–3 equiv. of EtSH.
Even at –20 °C, the formation of 5 or 6 was not observed,
but a large amount of insoluble material was always iso-
lated.
Compounds 3–6 are extremely air- and moisture-sensi-
tive, and they are readily soluble in dme, thf and toluene;
they are also slightly soluble in n-hexane. Elemental analy-
ses of 3–6 are consistent with the proposed formulas. The
1H NMR spectra in C6D6 at room temperature shows the
correct (Me3Si)2N–/StBu– proton ratios for 3 and 4 and the
correct (Me3Si)2N–/SEt–/thf proton ratio for 5, though the
proton signals of the (Me3Si)2N– and SEt– or StBu– ligands
are shifted significantly upfield owing to the paramagnetism
1
of these complexes. The H NMR spectrum of 6 contains
broad uninterpretable signals that give no useful infor-
mation about the solution behaviour of this paramagnetic
complex. The identities of 3–6 were finally confirmed by X-
ray crystallography.
Compound 3·2(thf)0.5 crystallizes in the triclinic space
¯
group P1 and the asymmetric unit contains half of the
[{(Me3Si)2N}2Pr(µ-StBu)]2 molecule and two halves of sol-
vated thf molecules, whereas 4 crystallizes in the monoclinic
space group P21/c and the asymmetric unit contains half of
the [{(Me3Si)2N}2Sm(µ-StBu)]2 molecule. As the molecular
structures of 3 and 4 are very similar, only that of 3 is
showed in Figure 1. Their selected bond lengths and angles
are compared in Table 1.
Scheme 1.
The protonolysis reactions of 1 and 2 with PhSH, tBuSH
or EtSH deserve comments. Treatment of 1 or 2 with an
equimolar amount of PhSH gave rise to a polymeric com-
plex [{(Me3Si)2N}2(µ-SPh)Pr(µ-SPh)Li(thf)2]ϱ and a tetra-
nuclear wine-cup-shaped complex [{(Me3Si)2N}4(µ4-Cl)-
Sm4(µ-SPh)4(µ3-Cl)4Li(thf)], respectively, whereas the reac-
tion of 1 with tBuSH or EtSH produced binuclear com-
Figure 1. Perspective view of 3 with labelling scheme and 50% ther-
mal ellipsoids. All hydrogen atoms are omitted for charity.
Compounds 3 or 4 consists of two {[(Me3Si)2N]2Ln}
plexes 3 and 4 or tetranuclear cationic complexes 5 and 6. moieties interconnected by a pair of µ-StBu anions to form
The remarkable difference in the outcome of these reactions a dimeric structure with a crystallographic centre of sym-
may be related to the steric effects of the R organic group metry at the midpoint of the Ln(1) and Ln(1A) atoms. Al-
(tBu Ͼ Ph Ͼ Et) bound to the S atom in the resulting struc- though the Pr2S2 core structure in 3 is uncommon in PrIII
tures. It is assumed that in the case of thiols that bear larger thiolate complexes, the analogous Sm2S2 core structure in
1890
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 1889–1896

Protonolysis Reactions of [(Me3Si)2N]3Ln(µ-Cl)Li(thf)3 with tBuSH or EtSH
Table 1. Selected bond lengths [Å] and angles [°] for 3 and 4.[a]
FULL PAPER
Ln = Pr (3)
Ln = Sm (4)
Ln(1)–N(1)
Ln(1)–N(2)
Ln(1)–S(1)
Ln(1)–S(1A)
2.292(3)
2.303(3)
2.8704(17)
2.8579(13)
2.272(8)
2.233(9)
2.786(3)
2.844(3)
N(1)–Ln(1)–N(2)
N(1)–Ln(1)–S(1A)
N(2)–Ln(1)–S(1A)
N(1)–Ln(1)–S(1)
N(2)–Ln(1)–S(1)
S(1A)–Ln(1)–S(1)
C(13)–S(1)–Ln(1A) 119.97(15)
C(13)–S(1)–Ln(1) 129.64(15)
Ln(1)–S(1)–Ln(1A) 110.39(5)
114.43(13)
131.27(10)
103.28(9)
99.84(9)
135.75(9)
69.61(5)
113.7(3)
137.1(2)
103.9(2)
103.2(2)
121.9(2)
71.54(9)
128.6(4)
122.9(4)
108.46(9)
[a] Symmetry code: A: –x+2, –y+2, –z+1 for 3; –x, –y, –z+1 for
4.
4 is found in some known dinuclear SmIII complexes such
[(thf)3I2Sm(µ-SC6H4(Me2N)-4)]2,[8]
[(C8H8)Sm(µ-
Figure 2. Perspective view of the anion of 5, where only the disor-
dered C(19)–C(20) atoms with a site occupancy factor of 0.45 are
shown. The thermal ellipsoids are drawn at the 50% probability
level and all hydrogen atoms are omitted for clarity.
as
SPh)(thf)2]2,[9] [Sm(C8H8)(thf)(µ-SC6H2iPr3-2,4,6)]2,[9] [Sm-
[10]
(SC6H2iPr3-2,4,6)(thf)3(µ-SC6H2iPr3-2,4,6)]2
and [Sm-
(SC6F5)2(thf)(µ-SC6F5)]2.[11] The Ln(1)···Ln(1A) separation
within the dimer in 3 or 4 is 4.703 or 4.568 Å, respectively,
which is too long to include any metal–metal interaction.
The structures of the anions of 5 and 6 have a square-
Each Ln centre in 3 or 4 is coordinated by two S atoms like Ln4 array that is linked by four pairs of SEt– ligands
from two µ-StBu– anions and two N atoms from two and is capped by a µ4-SEt– ligand above the Ln4 plane
[N(SiMe3)2]– anions to form a distorted tetrahedral geome- (0.919 Å for 5 and 0.953 Å for 6). This structure resembles
try.
that of [(thf)6Yb4(µ4-S)(µ-η2:η2-S2)4(SC6F5)2],[16a] [(thf)6-
In the Pr2S2 rhomb of 3, the two Pr–S bond lengths are Yb4(µ4-S)(µ-η2:η2-S2)4I2][16b] and Li[{(Me3Si)2N}4Nd4(µ4-
unsymmetrical with Pr(1)–S(1) of 2.870(17) Å and Pr(1)– Cl)(µ-SPh)8]·C6H6,[6a] which comprises a square array of
S(1A) of 2.858(13) Å. The mean Pr–S bond length of LnIII ions connected by four µ-η2:η2-S2 ligands or four
2.864(15) Å is comparable to that in [{(Me3Si)2N}2(µ-SPh)- pairs of SPh– ligands and capped by a µ4-S2– or µ4-Cl– ion
Pr(µ-SPh)Li(thf)2]n [2.831(5) Å].[6a] The mean Pr–N bond above the Ln4 plane. It is noted that the symmetries of the
length [2.298(3) Å] is close to that in [{(Me3Si)2N}2(µ-SPh)- structures of these compounds with the Ln4 core are quite
Pr(µ-SPh)Li(thf)2]n [2.312(5) Å],[6a] but slightly shorter than different owing to the different periphery bridging ligands
those found in [(Me3Si)2N]3Pr(µ-Cl)Li(thf)3 [2.359(3) Å][7b] and capping ligands. The structure of the anion of
and [Pr{N(SiMe3)2}4][K(thf)6] [2.428(5) Å].[12]
Li[{(Me3Si)2N}4Nd4(µ4-Cl)(µ-SPh)8]·C6H6 shows an ap-
In the Sm2S2 ring of 4, the two Sm–S distances are also proximate S4 symmetry whereas those of [(thf)6Yb4(µ4-S)-
not equal [2.786(3) Å and 2.844(3) Å]. The average distance (µ-η2:η2-S2)4(SC6F5)2] and [(thf)6Yb4(µ4-S)(µ-η2:η2-S2)4I2]
[2.815(3) Å] is close to those found in [Li(tmeda)2]- have an approximate C2v symmetry. However, the symmetry
[Cp*2Sm(SCϵCPh)2] [2.794(4) Å][5] and {(Cp2Sm)2Mo(µ- of the anions of 5 and 6 is C2 because of a µ4-SEt– ligand
S)4}(PPh4) [2.785(3) Å],[13] but slightly shorter than that in capping onto the Ln4 core. Although thiolates serving as a
[Sm(C8H8)(thf)(µ-SC6H2iPr3-2,4,6)]2 [2.881(5) Å].[9] The quadruply bridging ligand are found in several transition-
mean Sm–N bond length [2.252(8) Å] is somewhat shorter or main group metal–thiolate clusters such as [{Ag8-
than those in four-coordinate SmIII complexes (µ4-SC2H4-NH3)6Cl6}Cl2]n,[17a]
[Cu7{µ4-SCH2CH2NH-
SmL[N(SiMe3)2]2 {2.350(3) Å, L = N-tert-butyl-N-[2-(tert- (CH3)2}6(µ3-Cl)2(µ-Cl)13Cl2]n,[17b] [Cu4(µ-dppm)4(µ-NS2)-
[17c]
butylamino)ethyl]imidazolylidene}[14] and Sm[N(SiMe3)2]2- (µ4-NS2)]·CH2Cl2
and [{Tl7(µ4-Sthff)6}2(PF6)2]n (HSthff
(thf)2 [2.432(2) Å].[15]
= tetrahydrofurfuryl-thiol),[17d] the existence of a µ4-SEt–
Having a common chemical formula [Li(thf)4][{(Me3Si)2- ligand in 5 and 6 is unprecedented in the chemistry of lan-
N}4Ln4(µ4-SEt)(µ-SEt)8], 5·0.5C7H8 and 6·C6H6 crystallize thanide chalcogenolate complexes.
in the monoclinic space group P21/c with half of one tolu-
Each Ln centre in 5 and 6 is coordinated by one N atom
ene solvated molecule (5), and one benzene solvated mole- from the [N(SiMe3)2]– anion and one µ4-S atom and four
cule (6). As the structures of the [{(Me3Si)2N}4Ln4(µ4- µ-S atoms from the EtS– ligands to form a distorted octahe-
SEt)(µ-SEt)8]– anions in 5 and 6 are essentially identical, we dral coordination geometry. The mean Ln–µ4-S bond
only show the perspective view of the anion of 5 in Fig- length, 3.089(3) Å for 5 and 3.029(3) Å for 6, is much longer
ure 2. The pertinent bond lengths and angles for 5 and 6 than the corresponding Ln–µ-S bonds, which correlates
are compared in Table 2.
with the number of bonding interactions at the Ln centres.
Eur. J. Inorg. Chem. 2007, 1889–1896
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1891

M.-L. Cheng, H.-X. Li, W.-H. Zhang, Z.-G. Ren, Y. Zhang, J.-P. Lang
FULL PAPER
Table 2. Selected bond lengths [Å] and angles [°] for 5 and 6.
Ln = Pr (5)
Ln = Sm (6)
Ln = Pr (5)
Ln = Sm (6)
Ln(1)–N(1)
Ln(2)–N(2)
Ln(3)–N(3)
Ln(4)–N(4)
Ln(1)–S(1)
Ln(1)–S(2)
Ln(1)–S(7)
Ln(1)–S(8)
Ln(2)–S(1)
Ln(2)–S(2)
Ln(2)–S(3)
Ln(2)–S(4)
2.317(10)
2.314(12)
2.303(9)
2.316(12)
2.892(4)
2.865(5)
2.892(5)
2.865(4)
2.870(3)
2.866(4)
2.851(3)
2.894(3)
2.271(10)
2.262(13)
2.280(11)
2.304(13)
2.828(4)
2.861(4)
2.822(4)
2.807(4)
2.794(4)
2.835(4)
2.809(4)
2.820(4)
Ln(3)–S(3)
Ln(3)–S(4)
Ln(3)–S(5)
Ln(3)–S(6)
Ln(4)–S(5)
Ln(4)–S(6)
Ln(4)–S(7)
Ln(4)–S(8)
Ln(1)–S(9)
Ln(2)–S(9)
Ln(3)–S(9)
Ln(4)–S(9)
2.895(3)
2.916(3)
2.871(3)
2.860(3)
2.859(4)
2.872(3)
2.902(4)
2.869(4)
3.057(3)
3.163(3)
3.079(3)
3.058(3)
2.813(5)
2.831(4)
2.795(4)
2.846(5)
2.819(5)
2.842(4)
2.809(4)
2.818(4)
3.013(3)
3.092(4)
3.012(3)
2.998(3)
N(1)–Ln(1)–S(1)
N(1)–Ln(1)–S(2)
N(1)–Ln(1)–S(7)
N(1)–Ln(1)–S(8)
N(1)–Ln(1)–S(9)
S(1)–Ln(1)–S(9)
S(2)–Ln(1)–S(1)
S(2)–Ln(1)–S(7)
S(2)–Ln(1)–S(9)
S(8)–Ln(1)–S(2)
S(7)–Ln(1)–S(1)
S(7)–Ln(1)–S(9)
S(8)–Ln(1)–S(1)
S(8)–Ln(1)–S(7)
S(8)–Ln(1)–S(9)
S(4)–Ln(2)–S(9)
N(2)–Ln(2)–S(1)
N(2)–Ln(2)–S(2)
N(2)–Ln(2)–S(3)
N(2)–Ln(2)–S(4)
N(2)–Ln(2)–S(9)
S(1)–Ln(2)–S(4)
S(1)–Ln(2)–S(9)
S(2)–Ln(2)–S(1)
S(2)–Ln(2)–S(4)
S(2)–Ln(2)–S(9)
S(3)–Ln(2)–S(1)
S(3)–Ln(2)–S(2)
S(3)–Ln(2)–S(4)
S(3)–Ln(2)–S(9)
N(3)–Ln(3)–S(3)
N(3)–Ln(3)–S(4)
N(3)–Ln(3)–S(6)
98.9(3)
114.3(4)
98.3(4)
112.2(3)
101.2(3)
96.2(3)
S(5)–Ln(3)–S(9)
S(6)–Ln(3)–S(3)
S(6)–Ln(3)–S(4)
S(6)–Ln(3)–S(5)
S(6)–Ln(3)–S(9)
S(8)–Ln(4)–S(9)
N(4)–Ln(4)–S(5)
N(4)–Ln(4)–S(6)
N(4)–Ln(4)–S(7)
N(4)–Ln(4)–S(8)
N(4)–Ln(4)–S(9)
S(5)–Ln(4)–S(6)
S(5)–Ln(4)–S(7)
S(5)–Ln(4)–S(8)
S(5)–Ln(4)–S(9)
S(8)–Ln(4)–S(7)
S(6)–Ln(4)–S(7)
S(6)–Ln(4)–S(9)
S(7)–Ln(4)–S(9)
S(8)–Ln(4)–S(6)
Ln(1)–S(9)–Ln(4)
Ln(3)–S(9)–Ln(2)
Ln(1)–S(9)–Ln(3)
Ln(4)–S(9)–Ln(3)
Ln(1)–S(9)–Ln(2)
Ln(4)–S(9)–Ln(2)
N(3)–Ln(3)–S(5)
N(3)–Ln(3)–S(9)
S(3)–Ln(3)–S(4)
S(3)–Ln(3)–S(9)
S(4)–Ln(3)–S(9)
S(5)–Ln(3)–S(3)
S(5)–Ln(3)–S(4)
74.58(9)
80.07(10)
138.74(9)
70.06(10)
77.69(8)
81.65(11)
95.4(3)
82.98(10)
147.81(12)
111.83(12)
77.01(14)
68.16(10)
79.63(10)
114.4(4)
97.7(3)
95.6(4)
118.5(3)
155.6(3)
76.69(14)
146.42(13)
81.66(13)
82.84(12)
70.41(11)
115.55(12)
68.41(10)
74.31(10)
143.12(13)
85.98(9)
84.47(9)
144.39(11)
84.16(8)
82.68(8)
142.21(11)
113.1(3)
114.5(3)
156.9(3)
70.95(9)
70.39(11)
146.87(11)
82.51(9)
83.85(14)
111.83(10)
68.26(3)
144.26(11)
77.03(13)
81.74(9)
64.67(8)
103.7(3)
106.7(3)
106.0(3)
109.0(3)
168.3(3)
103.31(10)
69.68(9)
70.69(11)
144.14(12)
80.64(11)
147.49(11)
88.34(11)
79.06(9)
82.91(8)
112.6(2)
103.2(2)
117.5(2)
117.0(3)
157.3(3)
84.62(10)
77.61(11)
114.69(11)
66.46(9)
141.11(11)
146.70(12)
73.88(10)
81.06(12)
70.38(11)
79.54(10)
69.94(10)
106.5(3)
106.6(4)
106.9(4)
102.8(3)
166.2(3)
147.93(12)
83.73(10)
78.61(11)
105.36(11)
65.69(9)
88.04(13)
146.31(13)
71.00(12)
82.32(12)
113.2(4)
98.8(3)
120.1(3)
98.0(3)
115.2(3)
156.0(3)
70.05(9)
115.85(11)
145.65(12)
75.07(9)
76.81(12)
141.31(12)
77.85(8)
68.10(9)
80.69(11)
84.90(7)
83.08(7)
146.84(10)
86.41(8)
85.35(8)
143.93(9)
95.8(2)
158.7(2)
77.99(9)
83.69(9)
65.54(8)
146.00(10)
114.51(10)
156.9(3)
70.80(12)
83.72(11)
71.00(10)
84.54(15)
145.53(12)
98.4(4)
The average Pr–µ-S bond length [2.877(3) Å] in 5 is the caprolactone.[2j,6] Therefore, compounds 3–6 (Table 3) were
same as that in Pr[S2P(C6H11)2]3 [S2P(C6H11)2 = dicyclo- employed to initiate the ROP of ε-caprolactone at ambient
hexyldithiophosphinate, 2.877(4) Å].[18] The mean Sm–µ-S temperature. When the polymerization was performed in
bond length [2.822(4) Å] in 6 is comparable to those thf/toluene, a highly viscous product was observed to form
found in [{(Me3Si)2N}4(µ4-Cl)Sm4(µ-SPh)4(µ3-Cl)4Li(thf)] in less than 10 min. After the resulting polymers were
[2.822(4) Å],[6a] [(thf)Sm(SPh)3]4n [2.854(3) Å][19] and quenched by the addition of 1  HCl in EtOH, the poly(ε-
[Sm{O=P(NMe2)3}(SPh)3] [2.830(2) Å].[20] The mean Pr–N caprolactone)s were isolated as white solids and charac-
bond length [2.312(10) Å] in 5 is smaller than that reported terized by gel permeation chromatography. Compounds 3–
in Pr[Et2NCH2CH2NC(Me)CHC(Me)NCH2CH2Net2]Cl2 6 were found to initiate the ROP of ε-caprolactone at room
[2.5702(3) Å],[21] whereas the length of the Sm–N bonds temperature to give relatively high molecular weight poly-
[2.279(12) Å] in 6 is between those of [{(Me3Si)2N}4(µ4-Cl)- mers (Mn Ͼ 13400) with narrow molecular weight distribu-
Sm4(µ-SPh)4(µ3-Cl)4Li(thf)] [2.211(3) Å][6] and [{(Me3Si)2- tions (Mw/Mn = 1.17–1.56) in good yields within a few min-
NSm(µ-Cl)2Li(thf)2}(µ-Cl)]2 [2.284(4) Å].[22]
utes. For comparison, Table 3 lists the results for the ROP
Weak coordination of a soft-base sulfur atom to a hard- of ε-caprolactone initiated by 1–6 along with two known
acid Ln centre in lanthanide thiolate complexes is known PrIII and SmIII benzenethiolate complexes, [{(Me3Si)2N}4-
to be the cause for their catalytic behaviour in the ROP of ε- (µ4-Cl)Sm4(µ-SPh)4(µ3-Cl)4Li(thf)] (7) and [{(Me3Si)2N}2-
1892
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 1889–1896

Protonolysis Reactions of [(Me3Si)2N]3Ln(µ-Cl)Li(thf)3 with tBuSH or EtSH
Table 3. Polymerization of ε-caprolactone catalyzed by 3–6.
FULL PAPER
[c]
Entry[a]
Catalyst
Time
[min]
[Monomer]/[cat.]
Yield[b]
Mn
Mw
Mw/Mn
Ref.
[ϫ104 gmol–1]
[ϫ104 gmol–1]
[6b]
[6b]
1
2
3
4
5
6
7
8
1
2
3
4
4
5
5
6
6
7
7
8
20
20
1
1
2
1
2
2
9
400
400
400
400
100
400
800
400
600
400
600
400
59
46
2.71
2.93
6.31
4.13
1.77
4.50
1.34
5.34
2.42
3.41
3.33
2.61
5.55
5.83
9.12
6.30
2.76
5.55
1.70
6.42
2.83
4.94
5.09
3.70
2.05
1.99
1.44
1.53
1.56
1.23
1.27
1.20
1.17
1.45
1.53
1.42
100
100
100
100
100
100
100
99
this work
this work
this work
this work
this work
this work
9
this work
[6a]
10
11
12
8
15
20
[6a]
[6a]
75
99
[a] Temperature: 298 K; solvent: thf/toluene (1:4); Vε-caprolactone:Vsolvent = 1:5. [b] Yield: weight of polymer obtained/weight of monomer
used. [c] Determined by GPC analysis in thf, calibrated to a polystyrene standard.
(µ-SPh)Pr(µ-SPh)Li(thf)2]n (8).[6a] Complexes 3–6 showed
Experimental Section
better catalytic activity than their precursors, 1 and 2, which
may be ascribed to the weak Ln–S bonds in 3–6.[2g,2i,6] In
All manipulations were carried out under an atmosphere of argon
by using standard Schlenk techniques. All solvents were heated at
reflux and distilled from sodium benzophenone ketyl under an at-
addition, complexes 5 and 6 showed even better catalytic
activity than complexes 3 and 4 under the same reaction
conditions, which might be due to the fact that 3 and 4 have
mosphere of argon prior to use. [(Me3Si)2N]3Ln(µ-Cl)Li(thf)3 (1:
[23]
[24]
Ln = Pr; 2: Ln = Sm),[7] LnCl3
and LiN(SiMe3)2
were pre-
a less open coordination environment around the Ln metal
(coordination number four) than 5 and 6. Complex 3 and
its PrIII/benzenethiolate complex 8 had similar catalytic ac-
tivity for the ROP of ε-caprolactone. In the case of [mono-
mer]/[cat.] = 600, 6 initiated the polymerization of ε-capro-
lactone at a faster rate than its benzenethiolate analogue 7.
The former reaction was complete in 9 min with a 100%
yield whereas the latter was complete in 15 min with a 75%
yield. Therefore, we tentatively ascribed this difference to
the fact that the SEt– anions may be more easily dissociated
from the LnIII centres in 6 than the SPh– and Cl– anions in
7.
pared according to literature methods. tBuSH and EtSH were ob-
tained from commercial sources and used as received. ε-Caprolac-
tone, purchased from ACROS Com, was dried by stirring with
1
CaH2 for 8 d and then distilled under reduced pressure. H NMR
spectra were recorded at ambient temperature with a Varian UNI-
TYplus-400 spectrometer. 1H NMR chemical shifts were referenced
to the solvent signal in C6D6. Elemental analyses for C, H and N
were performed with a Carlo-Erbo CHNO-S microanalyzer. The
IR spectra were recorded with a Nicolet MagNa-IR550 FTIR spec-
trometer (4000–400 cm–1). Molecular weight and molecular weight
distributions were determined against a polystyrene standard by gel
permeation chromatography (GPC) with a Waters 1515 apparatus
with three HR columns (HR-1, HR-2 and HR-4); thf was used as
an eluent.
[{(Me3Si)2N}2Pr(µ-StBu)]2 (3): A solution of tBuSH (2.09 mmol)
in thf (1.65 mL) was slowly added to a solution of 1 (1.31 g,
2.09 mmol) in thf (20 mL). The mixture was stirred at room tem-
perature for 2 h, and then the solution was concentrated to dryness
in vacuo. The resulting solid was extracted with n-hexane (10 mL)
and toluene (20 mL) and then filtered. Compound 3·2(thf)0.5
(1.05 g, 43%) was isolated as light yellow crystals by cooling the
Conclusions
In summary, the protonolysis reaction of 1 or 2 with an
equimolar amount of tBuSH or EtSH was studied and ami-
dolanthanide alkylthiolate complexes 3–6 were isolated in
reasonable yields. Compounds 3–6 were characterized by
elemental analysis, IR spectroscopy and X-ray analysis.
Compounds 3 and 4 contain a Ln2S2 core structure whereas
5 and 6 consist of a square Ln4 array with one SEt– ligand
capping above the mean Ln4 plane. Occurrence of a µ4-SEt–
ligand in the structures of 5 and 6 is rare in the chemistry
1
filtrate to 2 °C for 3 d. H NMR (400 MHz, C6D6): δ = –7.17 [br.
s, w1/2 = 40 Hz, 18 H, C(CH3)3], –10.92 [br. s, w1/2 = 200 Hz, 72 H,
Si(CH ) ] ppm. IR (KBr disc): ν = 2960 (s), 2902 (m), 1635 (m),
˜
3 3
1385 (m), 1260 (s), 1189 (s), 1079 (m), 938 (s), 845 (s), 608 (w)
cm–1. C36H98N4Pr2S2OSi8 (1173.86): calcd. C 36.83, H 8.42, N,
of lanthanide chalcogenolate complexes. Compounds 3–6 4.77; found C 36.56, H 8.01, N 4.43.
showed better catalytic activity in the ROP of ε-caprolac-
[{(Me3Si)2N}2Sm(µ-StBu)]2 (4): Compound 4 (0.78 g, 40%) was
tone than their precursors 1 and 2 and their benzenethiolate
analogues. It is anticipated that 1 or 2 could react with
other thiols such as 1,2-diethanedithiol or cationic thiol
TabHPF6 [TabH = 4-(trimethylammonio)benzenethiol] to
afford other lanthanide thiolate complexes with more inter-
esting structural frameworks and better catalytic activities
in the ROP of ε-caprolactone. Studies on these respects are
underway in this laboratory.
isolated as light yellow crystals from the reaction of 2 (1.12 g,
1.75 mmol) with tBuSH (1.75 mmol) in thf followed by a similar
workup to that used in the isolation of 3. 1H NMR (400 MHz,
C6D6): δ = –0.90 [br. s, w1/2 = 32 Hz, 18 H, C(CH3)3], –2.00 [br. s,
w1/2 = 9 Hz, 72 H, Si(CH ) ] ppm. IR: ν = 2962 (s), 2903 (m), 1632
˜
3 3
(m), 1385 (m), 1258 (s), 1185 (s), 1084 (m), 938 (s), 848 (s), 613 (w)
cm–1. C32H90N4S2Si8Sm2 (1120.66): calcd. C 37.89, H 8.42, N 4.42;
found C 37.56, H 8.01, N 4.93.
Eur. J. Inorg. Chem. 2007, 1889–1896
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1893

M.-L. Cheng, H.-X. Li, W.-H. Zhang, Z.-G. Ren, Y. Zhang, J.-P. Lang
[Li(thf)4][{(Me3Si)2N}4Pr4(µ4-SEt)(µ-SEt)8] (5): A solution of EtSH with dimensions 0.14ϫ0.50ϫ0.30 mm were mounted in a sealed
FULL PAPER
(1.85 mmol) in thf (0.88 mL) was added dropwise to a solution of
1 (1.12 g, 1.85 mmol) in thf (20 mL). After stirring at room tem-
perature for 3 h, the volatile species were removed in vacuo, and
the crude product was extracted with toluene (20 mL) and then
filtered. The filtrate was kept at 2 °C for one week, which resulted
in the formation of light yellow crystals of 5·0.5C7H8 (0.440 g,
21%). 1H NMR (400 MHz, C6D6): δ = 3.25 (s, 32 H, thf), 1.27 (br.
s, w1/2 = 20 Hz, 27 H, CH3), 0.71 (br. s, w1/2 = 36 Hz, 18 H, CH2),
capillary, respectively. Diffraction data were collected with the ω
mode with a detector distance of 35 mm to the crystals. A total of
720 oscillation images for each were collected in the range 6.04° Ͻ
2θ Ͻ 50.70° for 3·2(thf)0.5, 6.28° Ͻ 2θ Ͻ 50.70° for 4, 6.10° Ͻ 2θ
Ͻ 50.70° for 5·0.5C7H8 and 6.18° Ͻ 2θ Ͻ 50.70° for 6·C6H6. The
collected data were reduced by using the program CrystalClear (Ri-
gaku and MSC, ver. 1.3, 2001), and an absorption correction
(multi-scan) was applied, which resulted in transmission factors
ranging from 0.385 to 0.485 for 3·2(thf)0.5, from 0.406 to 0.799 for
4, from 0.440 to 0.618 for 5·0.5C7H8 and from 0.359 to 0.694 for
–1.45 [br. s, w1/2 = 40 Hz, 72 H, Si(CH ) ] ppm. IR: ν = 2961 (s),
˜
3 3
2901 (m), 2184 (w), 1658 (m), 1520 (s), 1475 (s), 1385 (s), 1256 (s),
1179 (s), 1048 (m), 992 (m), 949 (s), 841 (s), 756 (m), 604 (s) cm–1. 6·C6H6. The reflection data were also corrected for Lorentz and
C61.5H153LiN4O4Pr4S9Si8 (2088.66): calcd. C 35.23, H 7.36, N 2.67;
found C 35.58, H 7.42, N 2.19.
polarization effects.
The structures of 3·2(thf)0.5, 4, 5·0.5C7H8, and 6·C6H6 were solved
by direct methods[25] and refined by full-matrix least-squares on
F2.[26] When crystals 3·2(thf)0.5 and 5·0.5C7H8 were taken away
from their mother liquors, rapid evaporation of part of the solvated
molecules in these crystals was observed. Although we made nu-
merous attempts, these crystals were always weakly diffracting, es-
pecially at high angles, which made the final R value relatively
higher. In addition, in the structures of 3·2(thf)0.5, 5·0.5C7H8 and
6·C6H6, serious disorder problems derived from the solvated mole-
cules and methyl groups from bis(trimethylsilyl)amide anions also
contributed greatly to the high R value. Therefore, the thf and C7H8
molecules in 3·2(thf)0.5 and 5·0.5C7H8 were fixed with constrained
parameters and refined with an occupancy factor of 0.5. For
5·0.5C7H8, three methyl groups bearing C(19), C(20) and C(21)
atoms were found to be disordered over two positions with an occu-
pancy ratio of 0.45:0.55 for C(19)/C(19A), C(20)/C(20A) and
C(21)/C(21A). In the case of 6·C6H6, a number of methyl groups
were found to be disordered over two sites with an occupancy fac-
tor of 0.58:0.42 for C(12)/C(12A) and C(16)/C(16A) and 0.54:0.46
for C(19)/C(19A), C(25)/C(25A), C(28)/C(28A), C(31)/C(31A),
C(34)/C(34A), C(35)/C(35A), C(36)/C(36A), C(38)/C(38A) and
C(41)/C(41A). All non-hydrogen atoms, except for those from thf
[Li(thf)4][{(Me3Si)2N}4Sm4(µ4-SEt)(µ-SEt)8] (6):
A solution of
EtSH (2.02 mmol) in thf (0.96 mL) was added dropwise to a solu-
tion of 2 (1.29 g, 2.02 mmol) in thf (20 mL). After stirring at room
temperature for 3 h, the volatile species were removed in vacuo,
and the crude product was extracted with benzene (20 mL) and
then filtered. The filtrate was kept at 2 °C for one week, which
resulted in the formation of light yellow crystals of 6·C6H6 (0.368 g,
1
17%). The H NMR spectrum in C6D6 showed broad uninterpret-
able signals. IR: ν = 2962 (s), 2905 (m), 2183 (w), 1655 (m), 1518
˜
(s), 1482 (s), 1385 (s), 1248 (s), 1181 (s), 1053 (m), 995 (m), 937 (s),
841 (s), 753 (m), 610 (s) cm–1. C64H155LiN4O4S9Si8Sm4 (2158.59):
calcd. C 36.61, H 6.86, N 2.60; found C 37.06, H 7.21, N 2.43.
Crystal Structure Determination and Refinement: All measurements
were recorded with a Rigaku Mercury CCD X-ray diffractometer
(3 kV, sealed tube) at 193 K by using graphite monochromated Mo-
Kα (λ = 0.71070 Å) light. X-ray quality crystals of 3·2(thf)0.5, 4,
5·0.5C7H8 and 6·C6H6 were obtained directly from the above prep-
arations. A light yellow chunk of 3·2(thf)0.5 with dimensions
0.45ϫ0.40ϫ0.30 mm, a light yellow prism of 4 with dimensions
0.40ϫ0.35ϫ0.10 mm, a light yellow prism of 5·0.5C7H8 with di-
mensions 0.22ϫ0.47ϫ0.30 mm and a light yellow prism of 6·C6H6
Table 4. Summary of Crystallographic data for 3·2(thf)0.5, 4, 5·0.5C7H8 and 6·C6H6.
3·2(thf)0.5
4
5·0.5C6H5CH3
6·C6H6
Empirical formula
Formula mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C36H98N4OPr2S2Si8
1173.86
C32H90N4S2Si8Sm2
1120.66
monoclinic
P21/c
12.067(2)
11.313(2)
23.486(7)
C61.5H145LiN4O4Pr4S9Si8 C64H147LiN4O4S9Si8Sm4
2088.66
monoclinic
P21/c
2158.59
monoclinic
P21/c
triclinic
¯
P1
11.396(2)
12.160(2)
12.366(3)
109.74(3)
99.50(3)
99.763(3)
1543.3(7)
1
1.263
612
18.1
14972
5595 (Rint = 0.0206)
5405 [IϾ2.00σ(I)]
249
0.033
0.095
0.987
2.53, –1.21
15.024(3)
25.455(5)
26.689(5)
15.039(3)
25.445(5)
26.357(5)
α [°]
β [°]
119.30(2)
99.60(3)
91.19(3)
γ [°]
V [Å3]
2790.0(12)
2
1.331
1156
23.5
25926
5104 (Rint = 0.0919)
4397 [IϾ2.00σ(I)]
217
0.084
0.171
1.178
2.72, –1.70
10206(3)
4
10084(3)
4
Z
Dcalcd. [gcm–3]
F(000)
1.359
4276
1.422
4392
µ [Mo-Kα [cm–1]]
Total no. of reflections
No. of unique reflections
No. of obsd. reflections
No. of variables
21.9
99290
26.1
97851
18652 (Rint = 0.0779)
13470 [IϾ2.00σ(I)]
18439 (Rint = 0.0839)
12599 [IϾ2.00σ(I)]
726
0.095
706
0.107
[a]
R1
[b]
wR2
0.231
1.089
0.245
1.437
GOF[c]
Residual peaks [eÅ–3]
1.51, –2.03
2.16, –2.70
[a] R = Σ||Fo| – |Fc||/Σ|Fo|. [b] Rw = {wΣ(|Fo| – |Fc|)2/Σw|Fo|2}1/2. [c] GOF = {Σw(|Fo| – |Fc|)2/(n–p)}1/2, where n is the number of reflections
and p is total number of parameters refined.
1894
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 1889–1896

Protonolysis Reactions of [(Me3Si)2N]3Ln(µ-Cl)Li(thf)3 with tBuSH or EtSH
FULL PAPER
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C(31), C(38), C(41)] in 6·C6H6 were refined anisotropically. Hydro-
gen atoms on C(43)–C(46) atoms in 5·0.5C6H5CH3 and C(43)–
C(46) atoms in 6·C6H6 were not located. All other hydrogen atoms
were placed in geometrically idealized positions (C–H = 0.98 Å for
methyl groups, C–H = 0.99 Å for methylene groups or C–H =
0.95 Å for phenyl groups) and constrained to ride on their parent
atoms with Uiso(H) = 1.2 Ueq(C) or 1.5 Ueq(C) for methyl groups.
All the calculations were performed with a Dell workstation by
using the CrystalStructure crystallographic software package (Ri-
gaku and MSC, Ver.3.60, 2004). Crystal and data collection param-
eters for 3·2(thf)0.5, 4, 5·0.5C7H8 and 6·C6H6 are summarized in
Table 4.
[4]
CCDC-624794 (for 3), -624795 (for 4), -624796 (for 5) and -624797
(for 6) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via http://www.ccdc.cam.
ac.uk/data_request/cif.
[5]
[6]
A Typical Procedure for the ROP of ε-Caprolactone: A 50-mL
Schlenk flask equipped with a magnetic stir bar was charged with
thf (0.33 mL), toluene (1.32 mL) and 5 (0.011 g). To this light yel-
[7]
low solution, ε-caprolactone (0.33 mL) was added at room tem-
perature by using a syringe and with vigorous magnetic stirring.
The stirring was ceased in a few minutes due to the viscosity. The
reaction mixture was quenched by the addition of 1  HCl in EtOH
after a fixed interval. The solution was then poured into petroleum
ether (20 mL) to precipitate the white oligomer. The resulting oligo-
mer was washed with methanol three times, collected and dried in
vacuo.
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Acknowledgments
[11]
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This work was supported by the NNSF of China (Nos. 20271036
and 20525101), the NSF of Jiangsu Province (No. BK2004205), the
Specialized Research Fund for the Doctoral Program of Higher
Education (No. 20050285004), the Qin-Lan Project of Jiangsu
Province and the State Key Laboratory of Organometallic Chemis-
try of SIOC (No. 06-26) in China.
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